FLOWERING PLANTS AND FERNS OF ARIZONA 603 



13. Echinocactus papyracanthus Engelm., Acad. Sci. St. Louis Trans. 

 2: 1S8. 1863. 



Mammillaria papyracantha Engelm. in A. Gray, Amer. Acad. 



Arts and Sci. Mem. ser. 2, 4: 49. 1849^ 

 Toumeya papyracantha Britt. and Rose, Carnegie Inst. Wash. 



Pub. 248. 3: 91. 1922. 



Near Showlow, Navajo County, about 6,500 feet (Bumstead in 

 1935), May. Northern New Mexico and Arizona. 



4. MAMMILLARIA. Fishhook cactus, pincushion cactus 



Small or low plants with short, solitary to numerous, turbinate or 

 hemispheric to cylindric, 1-jointed stems, these furnished with crossing 

 spiral rows of distinct teatlike tubercles; spines straight or hooked; 

 flowers borne in the axils of the tubercles or on the tubercles at the 

 base of a groove, funnelform, diurnal, lasting several days; hypan- 

 thium scales usually ciliate, not extending to the ovary; fruit a smooth 

 berry; seeds usually pitted. 



Key to the species 



1. Tubercles grooved from apex to middle or base; flowers borne at apex cf the 



stem, or laterally in M. recurvata (2). 



2. Spines yellow, the centrals more or less curved or even hooked; flowers 



yellow; berry green; seeds red or reddish brown, delicately reticulate or 



tessellate, shining (3). 



3. Tubercles short, crowded; central spines 1 to 2 cm. long, curved-reflexed; 



radials shorter, appressed; stems several to many, obscured by spines, 



10 to 20 cm. thick, broadly cylindric, the apex depressed; flowers borne 



well below the summit of the stem; berry about 8 mm. long; seeds 



1.5 mm. long 1. M. recurvata. 



3. Tubercles 15 to 30 mm. long, often with large glands in the grooves, widely 



spaced except toward the base of the stem; central spines 30 to 40 mm. 



long, stout, usually curved; stem not obscured by spines; fruit 4 to 



6 cm. long, slender; seeds 3.5 mm. long (4). 



4. Central spines 1 to 4, curved but rarely hooked; stem usually solitary. 



2. M. ENGEIiMANNII. 



4. Central spines 1 or rarely 2, stout, usually hooked; steins 1 to many. 



3. M. BOBTTSTISP1NA. 



2. Spines dark brown, whitish, or brown-tipped, straight; seeds red, pitted, 1 

 to 2.5 mm. long (5). 

 5. Flowers 2.5 to 3.5 cm. long, yellowish or pink; stems solitary or few. ovoid 



or cylindric 4. M. chloraxtha. 



5. Flowers 3.5 to 5.5 cm. long, pink; stems solitary, few, or numerous in con- 

 gested mounds, globose to ovoid (6). 

 6. Inner perianth segments oblanceolate, pale pink; central spines white 



with dark brown tips "__ 5. M. aggregata. 



6. Inner perianth segments lanceolate or linear-oblanceolate, darker pink; 



central spines mostly dark brown 6. M. arizoxita. 



1. Tubercles without a groove or shortly and indistinctly grooved at apex; flowers 



borne below the apex of the stem, or subvert ical in M. wilcoxii (7). 



7. Juice milky; stem turbinate or hemispheric; spines not hooked; seeds small, 



red, translucent, vertically rugose, the deep depressions (pits) elongate 



and about as wide as the ridges (8). 



8. Outer perianth segments erose or fimbriate; flowers greenish yellow; radial 



spines 9 to 15 13. M. macdougalii. 



8. Outer perianth segments entire, somewhat crispate; flowers pink; radial 

 spines about 2CL 14. M. heyderi. 



